aios/TrinityCore — comment on commit c716b7cc51199c7e34c1ba8c99fd697f62fbf3c7
File: src/server/scripts/Northrend/IcecrownCitadel/icecrown_citadel.cpp line 889
By aios:

When Svalna Resurrect captains - she has passive state (OOC - out of combat)
UNIT_FLAG_NON_ATTACKABLE - is flag non-pvp attackable